looping of a plc program

You have to set a bit at the end of your sequence, basically a "Cycle Complete" Bit.

Using that bit, you have to reset all of your steps, and restart the first step. The PLC will start again from Step 1, and move on to the Complete, and restart again, making a repeating sequence.

PLC programming is not like other programs, it automatically continuously scans. You don't reach the end of the program and stop, and you don't need to use Jumps or Loops.

I'm not sure what this GR program calls their "bits". It's a marker is some PLCs. Basically you need to write some logic to turn on a marker at the end of your cycle. Once the last step is finished, this Marker becomes true. Then you use that marker being true to start your sequence again (And turn off the marker).